农业工程学报2017，Vol.33Issue(2)：80-86,7.DOI:10.11975/j.issn.1002-6819.2017.02.011
加氯及毛管冲洗控制再生水滴灌系统灌水器堵塞
Chlorination with lateral flushing controling drip irrigation emitter clogging using reclaimed water
摘要
Abstract
Emitter bio-clogging has a close relation with the formation and growth of its internal clogging substances – the biofilms attached in the reclaimed water drip irrigation system. Chlorination with lateral flushing is one of the most effective measures to control the formation of biofilms within emitter, by using the chlorine to inhibit microbial growth and the shearing force to scour the clogging substances out of the system. Based on these, a field experiment using the reclaimed water treated with the cyclic activated sludge system (CASS) technology was carried out in the sewage treatment plant in order to study the controlling effects of 3 types of modes on emitter clogging, which were lateral flushing (flushing velocity was 0.45 m/s), chlorination (chlorination concentration was 5.00 mg/L) and chlorination with lateral flushing; chlorine and lateral flushing frequency were both once every 2 weeks (the time interval was 50 h). The result showed that chlorination with lateral flushing could effectively reduce the microbial contents in the attached biofilms within the emitters, as the phospholipid fatty acids (PLFAs) microbial content was 18.8μg at the second sampling, which was decreased by 52.2%, 44.2%, 73.2% compared with lateral flushing, chlorination and CK (the control, neither lateral flushing nor chlorination) treatment, respectively, and the secreted sticky extracellular polymeric substances (EPS) content was also reduced by 28.0%, 22.9%, 63.9%, respectively. EPS content was 0.47 mg at the second sampling, so that the total amount of clogging substances within emitter decreased by 47.4%, 43.1%, 69.1% with the joint action of the microorganisms and the secreted viscous polymer, thus making the emitter discharge ratio variation (Dra) and coefficient of uniformity (CU) improved by 40.0% and 53.0% respectively at the maximum, and the CU was kept more than 70%. The PLFAs microbial content and EPS content increased from the inlet of the drip irrigation lateral for the same treatment. The results also indicated that the content of EPS in the emitter did not show the same trend in comparison with the chlorination and lateral flushing. The effect of lateral flushing on the secretion of viscous EPS was better than that of chlorination treatment for the head part of emitter, but it was opposite for the middle and end part of emitter. Chlorination and lateral flushing could kill microorganisms, the species of microorganisms marked by PLFAs decreased obviously, and the microbial community structure in the emitter changed, but the types of dominant microorganisms were not changed. Thus it was more likely to delay chlorination starting time, and when the emitter Dra was reduced to 80%, chlorination could still reach a satisfactory controlling effect. Chlorination with the lateral flushing kills microorganisms and scours away the clogging substances at the same time, which makes the biofilm continued to grow and detach. But microorganisms produce resistance, and the production of resistant bacteria increases microbial activity to adapt to the changing external environment. So chlorination with lateral flushing increased microbial activity significantly by 36.5%, 29.0% and 15.7%, respectively, compared with lateral flushing, chlorination and CK treatment. It also decreased the recovery effect on emitter clogging gradually. In general, chlorination with lateral flushing can effectively control emitter clogging for drip irrigation using the reclaimed water treated with CASS.关键词
灌溉/微生物/加氯/灌水器堵塞/再生水/毛管冲洗Key words
irrigation/microorganisms/chlorination/emitter clogging/reclaimed water/lateral flushing分类
农业科技引用本文复制引用
宋鹏,李云开,李久生,裴旖婷..加氯及毛管冲洗控制再生水滴灌系统灌水器堵塞[J].农业工程学报,2017,33(2):80-86,7.基金项目
国家自然科学基金资助项目(51321001，51339007)；水利公益性行业专项经费项目(201401078) （51321001，51339007）
